<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Copyright (C) 2006-2023 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Funding Free Software", the Front-Cover
texts being (a) (see below), and with the Back-Cover Texts being (b)
(see below).  A copy of the license is included in the section entitled
"GNU Free Documentation License".

(a) The FSF's Front-Cover Text is:

A GNU Manual

(b) The FSF's Back-Cover Text is:

You have freedom to copy and modify this GNU Manual, like GNU
     software.  Copies published by the Free Software Foundation raise
     funds for GNU development. -->
<!-- Created by GNU Texinfo 6.7, http://www.gnu.org/software/texinfo/ -->
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Environment Variables (GNU libgomp)</title>

<meta name="description" content="Environment Variables (GNU libgomp)">
<meta name="keywords" content="Environment Variables (GNU libgomp)">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="makeinfo">
<link href="index.html" rel="start" title="Top">
<link href="Library-Index.html" rel="index" title="Library Index">
<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
<link href="index.html" rel="up" title="Top">
<link href="OMP_005fCANCELLATION.html" rel="next" title="OMP_CANCELLATION">
<link href="omp_005ffulfill_005fevent.html" rel="prev" title="omp_fulfill_event">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.indentedblock {margin-right: 0em}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
kbd {font-style: oblique}
pre.display {font-family: inherit}
pre.format {font-family: inherit}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
span.nolinebreak {white-space: nowrap}
span.roman {font-family: initial; font-weight: normal}
span.sansserif {font-family: sans-serif; font-weight: normal}
ul.no-bullet {list-style: none}
-->
</style>


</head>

<body lang="en">
<span id="Environment-Variables"></span><div class="header">
<p>
Next: <a href="Enabling-OpenACC.html" accesskey="n" rel="next">Enabling OpenACC</a>, Previous: <a href="Runtime-Library-Routines.html" accesskey="p" rel="prev">Runtime Library Routines</a>, Up: <a href="index.html" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Library-Index.html" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<span id="OpenMP-Environment-Variables"></span><h2 class="chapter">4 OpenMP Environment Variables</h2>

<p>The environment variables which beginning with <code>OMP_</code> are defined by
section 4 of the OpenMP specification in version 4.5, while those
beginning with <code>GOMP_</code> are GNU extensions.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top">&bull; <a href="OMP_005fCANCELLATION.html" accesskey="1">OMP_CANCELLATION</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set whether cancellation is activated
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fDISPLAY_005fENV.html" accesskey="2">OMP_DISPLAY_ENV</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Show OpenMP version and environment variables
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fDEFAULT_005fDEVICE.html" accesskey="3">OMP_DEFAULT_DEVICE</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the device used in target regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fDYNAMIC.html" accesskey="4">OMP_DYNAMIC</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Dynamic adjustment of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fMAX_005fACTIVE_005fLEVELS.html" accesskey="5">OMP_MAX_ACTIVE_LEVELS</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fMAX_005fTASK_005fPRIORITY.html" accesskey="6">OMP_MAX_TASK_PRIORITY</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum task priority value
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fNESTED.html" accesskey="7">OMP_NESTED</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Nested parallel regions
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fNUM_005fTEAMS.html" accesskey="8">OMP_NUM_TEAMS</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies the number of teams to use by teams region
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fNUM_005fTHREADS.html" accesskey="9">OMP_NUM_THREADS</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies the number of threads to use
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fPROC_005fBIND.html">OMP_PROC_BIND</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Whether threads may be moved between CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fPLACES.html">OMP_PLACES</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Specifies on which CPUs the threads should be placed
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fSTACKSIZE.html">OMP_STACKSIZE</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fSCHEDULE.html">OMP_SCHEDULE</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How threads are scheduled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fTARGET_005fOFFLOAD.html">OMP_TARGET_OFFLOAD</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Controls offloading behaviour
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fTEAMS_005fTHREAD_005fLIMIT.html">OMP_TEAMS_THREAD_LIMIT</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of threads imposed by teams
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fTHREAD_005fLIMIT.html">OMP_THREAD_LIMIT</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the maximum number of threads
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="OMP_005fWAIT_005fPOLICY.html">OMP_WAIT_POLICY</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">How waiting threads are handled
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GOMP_005fCPU_005fAFFINITY.html">GOMP_CPU_AFFINITY</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Bind threads to specific CPUs
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GOMP_005fDEBUG.html">GOMP_DEBUG</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Enable debugging output
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GOMP_005fSTACKSIZE.html">GOMP_STACKSIZE</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set default thread stack size
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GOMP_005fSPINCOUNT.html">GOMP_SPINCOUNT</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the busy-wait spin count
</td></tr>
<tr><td align="left" valign="top">&bull; <a href="GOMP_005fRTEMS_005fTHREAD_005fPOOLS.html">GOMP_RTEMS_THREAD_POOLS</a></td><td>&nbsp;&nbsp;</td><td align="left" valign="top">Set the RTEMS specific thread pools
</td></tr>
</table>


<hr>
<div class="header">
<p>
Next: <a href="Enabling-OpenACC.html" accesskey="n" rel="next">Enabling OpenACC</a>, Previous: <a href="Runtime-Library-Routines.html" accesskey="p" rel="prev">Runtime Library Routines</a>, Up: <a href="index.html" accesskey="u" rel="up">Top</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Library-Index.html" title="Index" rel="index">Index</a>]</p>
</div>



</body>
</html>
